Irix 15mm f/2.4 lens review (Nikon F mount)

This Irix 15mm f/2.4 lens for Nikon F mount review is by Bojan Stepančič (website: and it was originally published here. The post contains also some comparisons with the Nikon 14-24mm f/2.8 lens. Additional information on the Irix 15mm f/2.4 lens can be found here. The lens is currently in stock at Amazon UKAmazon DE and Amazon IT (still no US distributor).

Here is the review of the new Irix 15mm F2.4 lens. Switzerland-based company TH Swiss is a company behind this lens which is produced in Korea.
IRIX 15mm F2.4 comes in two versions “Firefly” and “Blackstone”, which have identical optics but slightly different housing. For a cheaper version Irix 15mm F2.4 Firefly lens housing is made of high quality and solid plastics, more expensive version of the Irix 15mm F2.4 Blackstone, has a magnesium and aluminium alloy housing.

Housing and construction

irix-15mm-f2-4-lens-review-2 irix-15mm-f2-4-lens-review-3 irix-15mm-f2-4-lens-review-6 irix-15mm-f2-4-lens-review-7
The lens barrel is in both versions excellent and very precisely manufactured. Focus ring is sufficiently large and rotates with exactly the right tension.

Lens allows the use of 95 mm screw-in filters at the front in the petal-shape lens hood and gelatin filters at the back of the lens.

Both versions of the lens are made of outstanding quality, I did not expect this from a lens in this price range.

Optical performance

Let me  first say, that despite a very affordable price, which is slightly over 400 euros for Firefly and around 600 euro for more expensive version – Blackstone, it is necessary to say that the optical quality of the lens is truly excellent. For the purposes of the test, I used a Nikon D610, which has a 24Mpix sensor.


Sharpness and contrast are excellent at all aperture settings and are very good even at the edges of the image. For comparison, I used a Nikon 14-24mm f2.8 lens.

On the photo below is a test site. Even on this photo, we could see that distortion of the lens is very low.

Sharpness of Irix lens at aperture f/2.4:

I compared sharpness between Irix and Nikon 14-24mm lens, at f2.8, f8 and f22. Nikon lens was set to 14mm.

Sharpness at f/2.8:

Sharpness at f/8

Sharpness at f/22:

As we can see from test photos, the difference between the two lenses is minimal. At aperture f22 Irix is even sharper than Nikon. On all settings Irix has slightly better contrast. Sharpness is excellent at all apertures and in the entire area of the image a little drop of sharpness could be seen only at the extreme corner of the image, which is great for both wide-angle lenses. Let me say that the Nikon 14-24mm f2.8 lens is one of the sharpest wide-angle lenses.

Optical distortion

I have to admit that the optical distortion of Irix lens is extremely well controlled. For comparison, I added the Nikon 14-24mm f2.8 lens.



Vignetting could be seen at the aperture f2.4. When we stop to f2.8 vignetting is almost gone.


Update on vignetting 28.06.2016

I did another test for vignetting. This time, I shot in M mode and noticed that exposition with f2.8 was off. At f 2.8 camera was overexposing so I had to change exposition time and it was same as with f2.4. Maybe a mechanical system for controlling aperture in camera and lens doesn’t make a difference in aperture settings between f2.4 and f2.8 with my Nikon cameras. This is a problem only with Firefly lenses.

Vignetting from f4 and up is very good controlled for UWA lens.

Chromatic aberration

I checked all photos and I could not find chromatic aberration on any photo. Here are two photos with high contrasts and no CA.


Ghosting and flare

Ghosting and flare are very well controlled. They could be seen only in extreme situations.



I am very surprised about the quality of the lens. Irix is an excellent lens, both “Firefly” and “Blackstone” are optically and mechanically excellent. Sharpness is excellent, distortion and vignetting are very well controlled,  no problems with  chromatic aberration, ghosting and flare are very well controlled. I hope they will produce more lenses like this in the future. Irix 15mm f2.4 is produced for Canon EF, Nikon F and Pentax K mount. Price for Irix 15mm f2.4 Firefly will be around 420 euro and 600 euro for Blackstone.

15mm wide angle lens gives you completely new photographic experience. Sometimes it could be difficult to find right compositions but once when you get used to the focal length and start to feel the compositions, things become easier. Thanks to low distortion of Irix lenses the photos could be very geometric in composition.

Gallery of photos taken with Irix 15mm f/2.4

This post was originally published here. Check also Bojan's review of the Nikon 105mm f/1.4E lens and many other Nikon reviews on his website.

If you have an interesting idea for a guest post, you can contact me here.

This entry was posted in Nikon Lenses, [NR] Reviews and tagged , , . Bookmark the permalink. Trackbacks are closed, but you can post a comment.
  • Eric Calabros

    Looking at size of air conditioning outdoor unit.. didn’t know the difference between 14mm focal length at 15mm is so noticeable.

    • Spy Black

      Different formulas have different FOV for a given rated focal length. Focal length numbers are rounded off too. Maybe the 15’s formula is more like a Nikon at 16.

    • akkual

      1mm makes huge difference on wide end, because it adds so many degrees more to the field of view. But I think in this case we are seeing the difference in distortion, not really in the focal length or degrees of FOV. Nikon at 14mm pulls center of the image closer and pushes borders far away, where as this IRIX has very little of distortion, hence AC unit on border looks significantly bigger on IRIX.

  • HF
    • Yu

      Yes and the result is so different on vignetting and flare

      • Nyarlathotep

        Agreed, the Vignette is pretty bad as shown on the Lenstip site. Not surprising given the FL, wide max aperture and smallish size of the front element.

        • Chris

          I noticed that in post processing vignette can be easily corrected. So what’s the real problem unless one shots film?

          • Nyarlathotep

            3 stops is a lot of correction. Layer that on top of other exposure adjustments, you may quickly be running out of noiseless adjustment headroom. And this is assuming a modern sensor. A D200 or something of that vintage and you are already in a bit of trouble with noise when correcting for vignette.

            • Pat Mann

              Contrast available is also a lot less in the area of extreme vignette, so if you’re trying to maintain a uniform appearance of a similarly patterned subject across the entire wide frame, you are challenged. Vignette correction definitely has its costs.

            • Chris

              Real world image from lenstip are not terrible as it seems.

              I also dont presume people will stare so hardly at the corners of a UWA shot. Once stepped down to f/5.6 it improves a lot. Now It all depends on whether you really need 15/2.5 for landscape…

              For a lens at this price, I am more concerned about where it can be practically used rather than wishing for the best for all purposes.

            • Nyarlathotep

              I think for more or less “affordable” fast UWA primes, in a lot of ways it comes down to more mustached distortion and flare (Samyang) or more vignette and softer corners (Irix). Build quality aside of course.

            • Soto

              I’ve just sent my Samyang 14mm back to Amazon and picked up the Irix Firefly and the corners are much sharper from f/5.6 onwards, which is what matters to me for landscape photography (plus no more wacky distortion corrections and I can shoot architecture).

  • BG

    I’m not convinced regarding flare resistance. I hope others will be able to shed some light on that (and also in comparison with the Tamron 15-30 and the Nikon 14-24).

    • Nyarlathotep

      Lenstip did their usual flair and ghosting test. It didn’t fair great, as to be expected with 15mm FL, but it did well enough given it is an UWA. Also, the Light falloff is massive at f/2.4 and at f/2.8. Even at f/4 its still -1.87 EV. I guess it is to be expected with the smallish front element.

  • Max

    Why is there such a broad plastic area around the front element?
    Is it because there is a bigger element just behind it?

    • Bob Thane

      It’s so they can use screw on filters without vignetting, I think.

  • Brimmith

    Does it make sense to test a prime lens against a zoom lens?

    • Michael Sullivan

      yes. mostly because the Nikkor 14-24mm is actually sharper than either the Nikkor 15mm or Nikkor 14mm.

    • Nyarlathotep

      In this case yes, because the 14-24 is such a good lens; but it would have been nice to see it up against the Zeiss 15 and the Samyang 14.

    • 247th

      The Nikon 14-24mm f/2.8 is the benchmark to which all other wide angle lenses (zooms and primes) are tested against.

  • Kyle

    All I know is that is some incredible performance at a great price. Will wait for some more reviews… but if they are generally positive like this, I’ll be getting one!

  • 247th

    I would recommend to others needing a budget ultra-wide. Not replacing my 14-24mm by any means though.

    • Wesley

      The Samyang/Rokinon 14mm 2.8 is the true budget ultra-wide and a bargain. I don’t consider this a budget lens or a bargain at those prices. I’m not saying it’s too high but I think the Samyang is a better deal and the Nikon is the best, most versatile. This falls somewhere between.

      • preston

        If the build quality is as good as advertised then this is absolutely a fantastic bargain UWA. The Samyang is awesome but I’d much rather pay a couple hundred more to get a lens I’m not worried about breaking every time I use it. Keep in mind this is half the price of the Nikon 14mm/2.8 and less than half of the 14-24/2.8.

        • Wesley

          It depends on the build quality of the Firefly version. That version is plastic and a “couple of hundred” more than the Samyang/Rokinon. The Blackstone version with the better build quality is $700+ US. That’s nearly 3x the Samyang. The Nikon 14 prime can be eliminated because it isn’t as good as the 14-24 zoom. Anyway…I still don’t consider either version of the Irix a bargain. They may not be bad deals but are nowhere close to the Samyang/Rokinon which can be had for $250 at times. I could change my mind if the Firefly version is considerably better in build quality but it would have to be significant for an additional $200+. I would probably eliminate the Blackstone version from consideration unless I plan to go to a place with more harsh conditions.

          • Kien Pham

            The strong point of Irix more than others are f/2.4, good controll of distortion and can fit 100mm system 2 slots square filters in the front

  • Plug

    I gather that the new Zeiss Milvus is better than its predecessor, so that will make an interesting comparison for those with the bucks. And it will be much more amenable to filters than its predecessor.

    • Pat Mann

      If you’re talking about the 15mm, it seems to be the same formula.

      • Plug

        That looks to be the case from the diagrams but a comment or two from early users suggest it may have been tweaked slightly for the better. We shall see in time if there is any change.

  • jmey

    Unfortunately this lens which is touted on their site as a astro lens does have coma issues in the corners, which for me at this price is not worth it. My samyang 14 2.8 will still be my goto astro lens

  • Gregory Wilson

    Thanks for sharing this review. Does this lens have a lens distortion correction profile already loaded or available to add to Lightroom? Downloadable? Capture One?

  • Achilleas Menos

    i wonder if,
    during the test of 14-24,
    the “distortion control” was “on” on the D610….?
    Nevertheless, Irix is a remarkable lens !

    • Bojan

      Distortion control was off during the test.

  • No coma test, NO POINT.

  • steven8217

    I just received my Irix 15mm F/2.4 Firefly plastic version, the feeling of the build quality is definitely higher than the Samyang 14mm/F2.8 and not far off to my Nikon 14-24mm/F2.8 but I believe my old Nikon 17-35mm/F2.8 has even better build quality albeit this old lens is not as sharp as my 16-35mm/F4 VR.
    Here are the 3 main reasons why I bought this Irix 15mm/F2.4 lens:
    1). It has an unique while your rotate the manual focus ring, it is very convenience to use this lens in the dark such as shooting Milky Way.
    2). It has a so I can lock the focus at any point as need, No more accidentally change the focus point once I lock down the focus point including locking the focus at Infinity at night.
    3). Irix will soon release the front filter, 95mm under its brand (hopefully with attractive pricing), such as the ND filter, Variable ND filter and CPL filter where the lens hook has an opening to rotate some of the filter as need.
    Irix will also release the rear filter, not sure at this point whether a glass or gelatin filter at 30x30mm (29x29mm with corner cut by 4mm if you prefer DIY).
    In contrast, it cost a lot more just to add a filter adapter for the Samyang 14mm or the Nikon 14-24mm.
    On the vignette concern, I guess the smaller front glass as compare to Samyang 14mm and Nikon 14-24mm could be the reason behind and also a compromise to accommodate a front filter, especially a CPL or Variable ND filter.
    F2.4 is very helpful for shooting Milky Way but I rarely set aperture at F2.4 for landscape so not a real concern, compare to the build-in filter thread capability.
    Note that you can just twist to remove the lens hook for easy storage with protection of the lens cap.I also like the lens pouch and the nice looking container that store the lens, Irix engineer have done a good job on paying attention to every details, even the nice looking rear lens cap 🙂 …….lastly, Irix did not offer me anything to write up my experience 🙂

    • vcize

      Thanks for the detailed write-up. Good info.

    • Kien Pham

      there are Laser100SE filter’s holder can fit 2 slots of square 100mm ND & GND in the front of lens, no vignetting even rotating 360o

      • steven8217

        HI Kien, thanks for the info, can you let me know where to get the 95mm adapter ring that will work with this Laser 100SE?

        • Kien Pham

          Because of spam rule, please google search : “Adapter for Irix 15mm f/2.4” or “Laser100SE” you will find what you need!

  • Enrico Celesti

    I received my blackstone copy last week. I’ve just sent it back after 2 days.
    The infinity click didn’t work very well, it didn’t focus at infinity.
    My copy wasn’t even sharp. Maybe the internal lenses were not well-aligned.
    Flares are not so well controlled as they say. If the sun is in the center or in the edges of the frame, many horrible frames appears.
    With a slim ND filter (4mm thin) the vignetting is huge.

    Bad copy, or 100% design and 0% optical quality?

    I don’t know if I should try to get a new copy, or maybe wait for the new samyang 14mm.
    I really liked the idea of a circular filter in a 15mm. 🙁

  • Back to top